Programmable focussed corona charger

Abstract

A corona charger can be programmed without physical adjustment to the charger, to give a plurality of desired characteristic plate current-to-potential curves so that one charger design can be used for a number of different charger formulations. The corona charger includes a conductive electrode and a corona wire between the electrode and the receiver. A variable duty cycle, pulsing voltage is applied to the electrode of same sign as the voltage applied to the corona wire, such that the corona charge produced by the wire is periodically accelerated by the electrode to the receiver.

What is claimed is: 
     
       1. A corona charger for charging a receiver, said charger comprising: a conductive electrode;   a corona wire between said electrode and the receiver;   means for applying a voltage to said wire, whereby a corona charge is produced; and means for   applying to said electrode a voltage of same sign as the voltage applied to said wire, said applied voltage pulsing between a low level such that the corona charge is   accelerated by the electrode to the receiver and a high level such that the corona shuts down.   
     
     
       2. A corona charger as set forth in claim 1 further comprising a non-conductive shell about said wire, said shell being open toward the receiver such that the corona charge is directed toward the receiver 
     
     
       3. A corona charger as set forth in claim 2 wherein said electrode is within said shell. 
     
     
       4. A corona charger as set forth in claim 1 wherein said means for pulsing the voltage to said electrode is a variable duty cycle, pulsing power supply. 
     
     
       5. A corona charger as set forth in claim 4 wherein said means for applying a voltage to said wire is a high voltage DC power supply.